CA2064420A1

CA2064420A1 - Process for the production of ultra-fine polymeric fibers

Info

Publication number: CA2064420A1
Application number: CA002064420A
Authority: CA
Inventors: Lloyd M. Robeson; Robert J. Axelrod; Jeffrey A. Kuphal; Timothy L. Pickering
Original assignee: Individual
Current assignee: Air Products and Chemicals Inc
Priority date: 1991-04-05
Filing date: 1992-03-30
Publication date: 1992-10-06
Also published as: US5164132A; EP0507205A2; JPH05106108A; EP0507205A3

Abstract

PATENT - 186PUS04350 ABSTRACT Ultra-fine polymeric fibers are produced from various polymeric materials by mixing with thermoplastic poly(vinyl alcohol) and extruding the mixture through a die followed by further orientation. The poly(vinyl alcohol) is extracted to yield liberated ultra-fine polymeric fibers. The polymer utilized can include post-consumer polymer waste.

Description

--``` 2 ~ 2 9 PATENT - l86PUS04350 ULTRA-FINE POLYMERIC FIBERS

FIELD OF THE INVENTION
The present inventlon relates to the productlon of ultra-flne flbers from various polymeric materlals includlng post-consumer polymer waste.

~KGROUND OF THE INVENTION
The need to recycle polymerlc materlals, especlally from the expandlng post consumer waste stream, is lncreasing as demands lncrease and avallable landfill sites cont~nue to decrease. Polymer1c mater~als are a small, but grow~ng fraction of the post consumer waste stream enterlng landflll sltes.
10 Polymer~c materials can, of course, be recycled and varlous programs and invest~gatlons are underway to lncrease the amount of recycled polymers and f~nd useful products where these mater~als can provlde a needed and useful functlon. Polymerlc constituents from the post consumer waste stream represent a new and unlque source of materials for polymer-type 15 applicat~ons. The recovery of polymers from thls source y~elds many dlverse type of products includ~ng a wlde range of polymer mixtures from almost pure constituents (e.g. poly(ethylene terephthalate) from carbonated beverage contalners and HDPE from milk bottles) to mixed c1asses (2.9. low denslty bottle scrap based on primarily polyolef~ns, h~gh denslty bottle scrap 20 contain~ng prtmartly poly(ethylene terephthalate) and poly(vinyl chlor~de>), to mixtures of all bottle materials and f~nally mixtures of all polymer scrap including poly(vlnylldene chloride), ethylene/v~nyl alcohol copolymers, cellulosic products (e.g. cellophane), high acrylonitrile copolymers (such as Barex (Sohio:BP) based on acrylol-itlilet~ethYl acrylate 25 used for food packaging) and the like. Many of the polvmers found in post consumer polymer scrap have solubility parameters greater than l0, for example one of the most common const~tuents, poly(ethylene terephthalate) has a solubility parameter of l0.6. The mechanical propert~es of comm1ngled polymers of widely ranging composit~ons are qulte poor and appllcatlons for 2 ~ 2 ~

commingled polymers generally fall in lowest range of cost/performance requirements for materials. These applications include flower pots, posts, lumber, fence slats, etc. In order to improve the properties of commingled polymer waste, Paul et.al. in Mod. Plast., 58, 60, (l9~l) noted that the styrene-ethylene/butylene-styrene ABA block copolymer commonly referred to as Kraton G yielded improved mechanical propert;es when admixed with polymer mixtures similar to that present in post consumer polymer waste.
Various processes for conversion of polymeric materials ;nto fine f;bers exist to meet the requirements of a myriad of applications. These 10 processes include melt-blowing processes to yleld fibrous materials, melt spinning technology, and polymer blend processes followed by extraction of one of the components.
Miller and Merriam note ~n U.S. Pat. 3,0g7,99l that a polymer pulp can be made by extrusion of immiscible polymers followed by a paper beating type operation to separate the immiscible fibers. These fibers could then be dispersed 1n water and a polymer pulp could be made. The use of a solvent for one o~ the constituents of the immiscible polymer blend to liberate the fibers was noted in a similar patent by Merriam and M~ller (U.S. Pat.

3,099,067). This patent discussed methods to make ultra-fine fibers of polyethylene, polychlorotrifluoroethylene, or polyamides. U.S. Patent 3,382,305 discloses a process for the formation of oriented materials conta~ning microfibers by blending at least two incompatible fiber-forming polymers via extrusion followed by drawing (orienting) and optionally dissolving one of the polymers from the resultant fibrous material. None of 2~ these references discuss or disclose the potentlal utility of polymer scrap or the utility of poly(vinyl alcohol) as a water soluble matrix for the production of fine fibers.
Japanese patent application Showa 47-67754 discloses a method for manufacturing fine flbrlls containing poly(v~nyl alcoho1). They disclose a method involv~ng mixing poly(vinyl alcohol) w~th 20-95X of one or more polymers with a solubility parameter of lO (cal/cc)l/2 or less and extruding and drawing the extruded mixture. The resultant drawn article is then beaten ~n water conta~ning an ~norganic salt to prevent the foaming and extraction of the poly(vinyl alcohol). They note that mixtures of 2 ~ 2 ~

polyethylene and polypropylene can be utilized in this process. They do not disclose the potential of using post-consumer polymer scrap nor the use of defoaming agents. Additiona11y, the disclosed process specifically does not remove the PVOH from the resultant fibers, in fact, the patent takes procedures to prevent removal of poly(vtnyl alcohol).
Japanese Patent Appltcation No. Showa 44-20869 dtscloses the method of manufacturing water-containing poly(vinyl alcohol~ powder and a thermoplastic ltnear polymer powder by mixing them, followed by thermal fusion and extrusion. Molded articles were the subject of this invention lo and neither extraction of the poly(vinyl alcohol) nor fiber productlon from the extracted blend was carried out.

$UMMARY OF THE INVENTION
The present invent~on is a process for mak~ng ultra-fine polymer~c fibers which are useful in a wide variety of end use applications. Such polymeric fibers are produced by mixing immiscible granular thermoplastlc polymertc material with thermoplastic poly(vlnyl alcohol) and extrud~ng the resultant mixture through an extrusion die to partially or~ent the tmmiscible polymeric material tnto rods. The mixture ls subsequently subjected to a further orientatlon step to orient the lmmisctble polymeric mater~al into polymeric f~b2rs. The thermoplastlc poly~vinyl alcohol) ls then extracted to produce ultra-f~ne polymeric ~tbers. Optionally, the extracted poly(vinyl alcohol) can be removed and recycled in this process.
The invention herein notes a process ~hereby a polymer blend approach 25 ls utilized employing a water soluble polymer which is biodegradable and tmmiscible with the vast ma~ority of polymers ~or whtch ultra-fine f;bers are desired. The water soluble polymer employed is thermoplastic poly~vtnyl alcohol) whlch offers a property balance spectflcally des~red for this process. The ultra-fine ~ibers from this process offer utility as fibrous thtxotropes, oil spill contalnment, water sorption, composites wtth wood pulp based products, polymer paper, ultra-~tne filters, insulation, as well as admlxtures with woven fabrics to yield spectflc property modlf~cations.
Spectfic polymers (e.g. polypropylene, polyethylene, po1ystyrene etc.) and admixtures thereof are of interest for the ultra-fine ~tbers produced by the ~ o ~

process noted in thls inventionO Additionally, post-consumer polymer waste ;s an important polymeric material to be ut~lized in this process.
Unlike the teachings of the prior art, the present process is capable of producing useful products in fibrous form from hi~hly heterogeneous streams, i.e., post consumer scrap, and can even tolerate the presence of paper residue in the starting material without experiencing severe problems resulting from degradation of the paper during the extrusion process. By employing thermoplastic poly(vinyl alcohol) which is capable of being highly or~ented ev n with large amounts of additional polymeric material and subsequently extracting the poly(v~nyl alcohol) from the resultant f~bers, useful ultra-f~ne f~bers can be produced from polymeric material which otherw~se would be discarded.

DETAILED DESCRIeTIQN OF THE INVENTION
The present invent~on is a process for producing ultra-fine fibers from a wide variety of polymeric materials. The process comprises mixing immis-c~ble granular therxplastic material w~th ther~oplastic poly(vinyl alcohol) (PWH) and 0xtruding the resultant mlxture through a die to partlally orient the 1mmiscible polymeric material into rod-l~k2 structures. The extrusion of the thermoplastic poly(vinyl al~ohol) and the thermoplastic polymer can be conducted in conventional polymer extrusion equipment. The die desSgn can be optimized to yield extensional flow to allow for orientation in the die. The mixture is then subjected to a further orientation step to form polymeric f1bers. Thls further orientation step can be any techn~que wh~ch ls capable of orienting polymeric material in solution to form fibers. Such methods lnclude hot drawing and/or cold draw~ng techniques known to those skilled in the art. Following the orientat~on step, the poly(v~nyl alcohol) ~s extracted, by any suitable method sufficient to remove substantially all of the PWH such as by agitatlon ln a water slurry, to produce ultra-f1ne polymeric flbers.
The present process is espec~ally advantageous ln that useful ultra-fine fibers can be formed from a wide variety of thermoplastic polymeric mater~als, lnclud~ng polymer scrap found in post consu~er waste streams.

-` 2~6~L4~

The thermoplastic polymeric materials can include polyolefins such as polypropylene, polyethylene (lnclud~ng hlgh density polyethylerle, low density polyethylene, linear low density polyethylene, linear very low density polyethylene, ethylene-propylene copolymers, ethylene-ethyl acrylate copolymers, ethylene-acrylic acid copolymers, ethylene-vinyl acetate copolymers, ethylene-methacrylic acid copolymers and ionomers), polystyrene, styrene copolymers (e.g. styrene-acrylonitrile copolymers), poly(methyl methacrylate)~ poly(vinyl acetate), polycarbonates, poly(butylene terephthalate)t poly(ethylene terephthalate), nylon 6, nylon 11, nylon 12, nylon 6,6, as well as other polymers immiscible with poly(vinyl alcohol).
Blends of these polymers are contemplated 1n th~s invention. Polymer scrap materlal, for wh~ch the present process is par~cularly advantageous, will typlcally include one or more of the ~ollowing: poly(ethylene terephthalate); poly(v~nyl chloride); polyolef~ns such as high density polyethylenc (HDPE), low dens~ty polyethylene (LDPE), and polypropylene;
h~gh acrylonitr~le copolymers; poly(vinylidene chloride~; ethylenelvinyl alcohol copolymers; cellulos~c products, polystyrene, ABS, and mixtures thereo~, as well as any si~ilar polymeric materlal. The ultra-fine f~bers produced by th1s process can be processed ~nto a wide variety o~ end products, thereby providlng a useful alternat1ve to the disposal of such scrap mater~al.
The poly(vlnyl alcohol) uti1~zed ~n this process is prepared from the hydrolysls of poly(vinyl acetate). The preparation of poly(vinyl acetate) and hydrclysis to poly(v;nyl alcohol) is well knswn to those skilled 1n the art and are discussed in deta~l in the books "Poly(vtnyl alcohol):
Prop~rti~s and Applicat~ons," ed. by C. A. F~nch, John Wi1ey & Sons, New York, 1973 and "Poly(v1nyl alcohol) F~bers," ed. by I. Sakurada, Marcel Dekker, Inc., New York, 1985. A recent rev~ew of poly(vlnyl alcohol) was given by F. L. Marten in the Encyclopedia of Polymer Sclence and Eng~neering, 2nd ed.j Vol. 17, p. 167, John W~ley & Sons, New ~ork, 1989.
As noted ~n this reference, several patents clai~ the preparation of extrudable poly(vinyl alcohol) utilizlng high boiling water-soluble organic compounds containing hydroxyl groups. These compounds (e.g. glycerol, low molecular we1ght poly(ethylene glycols)~ are plasticizers which lower the 2 ~ 2 ~

melting polnt of poly(vinyl alcohol) into a processible range. Other suitable plasticizers such as sulfonamides can be considered if they are high boiling and miscible with poly(vinyl alcohol).
Prior to being mixed with the thermoplastic PVOH, the thermoplastic polymeric material, if not already in granular form, is ground, typically by mechanical or cryogenic grind~ng techniques, to form granular flakes. The polymeric granules are mixed to form a blend with PVOH which serves as an extractable matrix for the production of the fibersO The use of PWH in this process is critical in that it ls water soluble, is immiscible with the primary components of the polymer waste, is capable of being highly oriented even 1n the presence of large amounts of added polymer scrap and is bio-degradable. All of the above attributes are necessary for the successful operation of the present process. Add~tionally, the PVOH used in th~s process 1s requ;red to be thermoplastlc in the range of 170-230C. To ach~eve th~s requ~red thermoplastic behavior (i.e. reduct~on of the melt~ng point to a processable range), plasticizers wh~ch are high boiling, water-soluble organi~ compounds containing hydroxyl groups, such as glycerol, low molecular weight poly(ethylene glycols) and the 11ke are added to the PVOH.
The preferred range of hydrolysls of the PVOH for utility in this invention is between about 72-99X, and preferably from 78-94%. Other water soluble polymers can also be added such as poly(v~nyl pyrrol~done), poly(ethyl oxazoline) and poly(ethylene oxide).
Optionally, a defoamlng agent, can be added to the PYOH/polymeric mixture to reduce or prevent foaming during Pxtraction process as noted in U.S. Patents 4,844,709 and 4,845,140. Preferred are ethylenQ
oxide/propylene oxide block copolymer sur~actants with surface tensions between 40 to 48 dynes/cm as a 0.1 aqueous solution at 25C.
The in~tial extrus;on through the d~e results in partial orientat10n of the polymeric material into short strands or rods. In order to form long, cont1nuous ultra-f1ne f1bers tne mixture ls subjected to a further or~enta-tion step. This orientation step is carried out by hot drawing and/or cold drawing procedures known in the art. The orientation step results in ultra-fine polymeric f~bers in PWH.
The extruslon of the thermoplastic poly~vinyl alcohol) and various polymers ~nto cyl~ndrical structures through a c~rcular d~e is a preferred 2 ~

embodiment of this invention. Other preferred geometries include slot dies and film dies to yield tapes and films which are also oriented via hot drawing or cold draw~ng procedures. Other geometr~ QS, ( e.g. ellipsoidal) can also be contemplated in this invention. Th~ resultant oriented structures can be chopped into convenient lengths. The resultant pellets, chopped tapes or films can be added to water and optionally allowed to soak in water (cold or hot) and then adde~ to a dev~ce to provlde shear to separate the fine fibers from the poly(vinyl alcohol). This equipment can include various blenders equipped with agitat~on devices includ~ng those co D nly utilized in the pulp and paper industry to beat wood part~cles into pulp. The foaming wh~ch results can be controlled by the addition of an ant~foam for poly(vinyl alcohol) known in the art and also described ln U.S.
Patents 4,844,709 and 4,845,140. The addlt~on of antifoam is however not necessary if closed vessels are employed for the agitation of the poly(v~nyl alcohol) fine fiber composite. Indeed, the foam~ng may yield improved liberation of the fibers. The resultant agitated blend consisting of liberated fibers and extracted poly(vinyl alcohol~ dissolved 1n the water phase can be separated vla filtration uslng porous mesh screens sr other appropriate filtration media. The extraction process can be repeated (with optlonally further ag~tat10n) to remove poly(vinyl alcohol). This process can be repeated several times depend~ng on the level of poly(vinyl alcohol) removal desired. The extracted poly(v~nyl alcohol) can be recovered, dried and recycled ~n this process. Counter current extraction processes utilizing water fed to the last extraftion stage and recovered and utilized in the other stages. The most concentrated poly(vinyl alcohol) extract will come from the first stage wh~ch can then be recovered for reuse in this process or recovered for utll~zation in other poly(v~nyl alcohol) appl~cations. The resultant extracted f~bers can be dried and ut~lized in the varlous appllcations noted in this disclosure as well as any other applications for whlch the ultra-fine fibers of this 1nYention may be suitable. We have found, unexpectedly, that by v~gorously extractlng the PVOH from the polymeric fibers, the resultant f~bers are su~table for a wide varlety of end-use appl1cations such as asbestos replacements, use in fibrous th~xotropes, rein~orcement additives for cement, caulks, mastics, 2 ~ 2 ~

adhesives, coatings and the like. The use of thermoplastic PVO~ to orient ~he f~bers and, unlike the prior art, subsequently extracting the PVOH from the formed fibers, allows the present process to produce useful fibers from varlous polymers includlng heterogeneous scrap material, even in the presence of non-thermoplastic contaminants, such as paper residue.
Another advantage of using thermoplastic PWU is, as stated above, that lt ~s biodegradeable and therefore does not present a serious environmental problem relating to disposal in a waste stream. Notwithstanding this fact, we have found that the extracted PVOH san be recycled and reused in the or~g~nal m1xing step with add1tlonal scrap material, thus reduc~ng cost and waste and lncreasing process efficiency.
The following examples are presented to better illustrate the present invention and are not meant to be llmiting.

Exam~
A blend of pellets/powder of the following composition was prepared 50X V~nexTM 2025 PVOH (a thermoplast~c PWH manufactured by A~r Products and Chemicals, Inc.) lOX Polystyrene Aldrich Chem Co. Mw ~ 250,000 lOX Polypropylene Profax 6523 (H~mont) lOX LLDPE

The HDPE was from Exxon (Melt Flow ~ 2.3 dg/min (190C, 44 ps~)) and the LLDPE was from Exxon (Melt Flow ~ 6.9 dg/min (l90, 44 ps~)~
The dry blended pellets/powder were fed to a l" diameter Killlon extruder (L/D ~ 30) and extruded at 390~F. The resultant extruded product was drawn and cooled by contacting with dry ice and followed by chopping into Nl/8" pellets. The pellets were immersed in water and rapidly agitated using a Waring blender. The product was separated from the water and the fibrous mass was squeezed to remove excess water and dissolved PVOH. This procedure was repeated several times to remove resldual PWH. Scann~ng electron microscvpy revealed fiber d~ameters in the range of l~. This mixture was utllized to simulate polymer scrap sim~lar to compositions which could be present from post-consumer waste streams.

2~6~0 _ 9 _ Exam~l* 2 A sample of NJCT was obtained ~or evaluat~on in this process. NJCT
(New Jersey Curbside Tailings) is an actual polymer waste stream comprised of polymer conta~ner scrap after the HDPE milk bottles and the PET
(poly(ethylene terephthalate)~ carbonated be~erage bottles have been removed. This product consists primarily of HDPE with some polypropylene, poly(vlnyl chlorlde) and poly(ethylene terephthalate). A further descript~on of this product ls giVQn 1n Plastics Engineering, p. 33, Feb.
1990. The polymer flakes are somewhat contaminated w~th paper as well as with res~dual bottles contents (e.g. detergent, etc.). This product was added to water and the flakes which ~loat~d were removed and dried.
mixture of 50~ Vinex 2025 and 50~ (by we1ght) of the NJCT flakes (which floated on ~ater) was extruded at 390C in the Kill~on extruder noted in Example 1. The resultant extrudate was drawn and cooled over dry ~ce. The pelletlzed product was lmmersed in water and agitated in a ~aring blender to extract the poly(vinyl alcohol~ and 11berate the fine fibers generated via ~his process. The resultant extracted product consisted of fine f~bers as observed vlsually and by scanning electron microscopy.

Example ~
The polymer NJCT flakes as received w~re washed, dried and ground to f~ne particles via liquid nitrogen grlnding. A blend of 50X Vinex 2025 PVOH
and 50X NJCT powder was extruded as per example 2. The resultant drawn, pelletized blend was agitated in a water slurry in a Waring blender to remove the poly(vinyl alcohol) and ~ree the f~brous structure of the NJCT
component. The resultant extracted product was comprised of fine flbers.
The PET powder from this process did not fibr111ate but did not interfere w~th the rest of the product.

Example 4 A simulated polymer scrap mixture comprised o~ a large number of polymer~c mater~als was blended with thermoplastic poly(vinyl alcohol) in the following proport~ons.

2~4~

SOX V1nex 2025 PVOH
lOX Polystyrene (see example 1) 5~ Polypropylene Profax 6523 (Himont) 5~ LLDPE (s~e example 1) 5X HDPE tsee example 1) 5X PMMA (Plexiglas DR-100~ (Kohm & Haas~
lZ Noryl SE-100 (General Flectric) 1.5X Poly~vinyl acetate) 4~ Ethylene/acrylic acid copolymer EM-1410 lDow Chem~cal Co.) lo 10% LDPE (Norchem) 3.5X PVC 1185 (~3~ ~M-181) ~Alr Products and Chemicals, Inc.~

The resultant blend was extruded as per example 2, drawn, and pelletized.
The fibrous product was liberated from the thermoplastic poly(vinyl alcohol) lS matrlx via agitation in a Waring blender. The resultant extracted proJuct consisted of f~ne fibers as noted in the prior examples.

Exam~le 5 A sample of the extruded, orlented pellets of example 1 was d1spersed in a quart of water and allowed to set for 4 hours. The sample was further diluted a~d agitated in a pulp d~sintegrator. Antifoam was added to lower foaming. After several extract~ons, several hand sheets were prepared in a laboratory hand sheet apparatus. Also wood pulp was blended with the polymer fibers ~n the pulp disintegrator followed by handsheet preparation.
A uniform mixture of the wood and polymer fibers was obtained. Th1s experiment demonstrates the abil~ty to use the product of this inventlon ~n pap2r making equlpment, and to m~x the product of th~s invention with wood pulp.

Example 6 Paper Handsheets with SYnthetic Pul~ Added A synthetic pulp prepared from the simulated polymer waste product of Example 1 was used ~n conjunction with a long f~bered unbleached Kraft pulp to prepare compos~te paper handsheets. Handsheets containing 10, 20, and 30 weight percent synthetic pulp were prepared as ~ollows.

2~6~2~

Twenty four grams of the synthetic pulp/Kraft pulp mixture were soaked in 2 liters of water for 3 hours. The slurry was then disintegrated for 17 minutes in a British Standard Pulp Disintegrator operat~ng at 3300 rpm. The slurry was diluted to 7.2 liters and 400 ml portions were taken for handshee~ formation. The handsheets were prepared on a British Standard Handsheet Former following TAPPI Method 205. The synthetic pulp formed an intimate mixture with the Kraft pulp and there was little tendency for the less dense synthetic pulp material to segregate or ~loat. A~ter pressing and drying, the synthetic pulp was v1sually apparent ln the sheets but appeared to be uniformly dispersed throughout.
Representative samples fro~ each set of handsheets were given an additlonal heat and pressure treatment to bond the plastic flbers together.
Treatment condit~ons were 2 m~nutes at 120C and 3000 psi pressure using a Carver press. The handsheets were tested for wet and dry tensile strength following TAPPI Method 494. The results are shown in Table 1.

- 2 ~ 2 ~

_ 12 -KRAFT/SYNTHETIC_PULP HANDSHEETS
Physical Properties Data Heat Treated Samp]es_ Test Con~rol lOX 20X 3QX ÇQn~QL lOX _20X 30X
Gram~age 144.1 148.0 147.1 137.4 144.1 148.0 147.1 137.4 glm Bas~s ~e~gh~ 29.5 30.3 30.1 28.1 29.~ 30.3 30.1 28.1 lb/1000 ft Dry T.S., lb/in23.0 17.2 14.1 3.0 20.2 21.0 23.5 20.7 kN/m 4.0 3.0 2.5 1.6 3.5 3.7 4.1 3.5 Wet T.S., lb/in0.9 0.9 0.8 0.7 0.9 1.7 2.9 4.3 kNlm 0.2 0.2 0.1 o.~ 0.2 0.3 0.5 0.8 Tens. Index, N~/g 27.9 20.3 16.8 11.5 24.5 24.8 28 26.4 Wet TI, Nm/g 1.1 1.1 1.0 0.8 1.1 2.0 3.5 5.5 ~et/Dry, X 3.9X 5.2X 5.7X 7.3X 4.5X 8.1~ 12.3X 20.8 Breaking Length, 2794 2035 1678 1147 2455 2485 2797 2638 meters The as-prepared handsheets suffered a loss in dens~ty and dry strength as a result of synthetic fiber addltion. Th~s ~s attrlbuted to interference ~ith wood to wood flber bonding by the hydrophoblc polymer fibers. The tenslle strength was reduced in proportion to the amount of synthetic fiber used.
In contrast, the thermally treated samples showed no loss in dry tensile strength compared to the control, and the wet tens11e strength was increased by as much as 460X. Th1s ~s attributed to thermoplastic bonding of the synthetk fibers with each other and perhaps with wood f~bers as well. Thus the thermally treated composite handsheets display a superior balance of propertles compared to Kraft handsheets contain~ng no synthetic pulp.

2 ~

_ 13 -_xam~le 7 Prepara~i~n of ~ynth~lc Pul~ Fel~ Mat~
Twenty-four grams of synthetic pulp from Example 1 was soaked in two llters of tap water for three hours. Although composed of hydrophobic p1astic fibers, the pulp read11y absorbed water. The slurry was mixed for five m~nutes in the pulp disinte~rator to thoroughly disperse the fibers in water. However, on standing the f~bers soGn floated to the sur~ace because of the~r low density.
Samples were d1pped from the slurry and formed into mats uslng th~
Br~tish Standard handsheet former followlng TAPPI Method 205. Becaus~ there are no interfiber bonding forces as ~s the case with wood fibers, the synthetic pulp mats had very l~ttle strength and were difficult to remove from the dra~ning wire wlthout breaklng into piecesO Slmilarly, the drled mats were of low density and strength; however, with suitable care they could be handled without damage.
The fiber mats are useful as absorbent pads, e.g. as clean-up aids for oll spills, aqueous chem~cals, etc.

Exam~le 8 A m~xture o~ 55X Vinex 2025 PWH and 45X ProfaxTM 6523 polypropylene was extruded ln a 1" K~llion s~ngle screw extruder (L/D ~ 24/1~ at 200C.
The extruder RPM was 36, the produft rate was 5.3 lbs/hour and the strand rate (2 strands) was 17 ft/minute after draw~ng. The sample was hot drawn and cooled on steel rollers prior to pellet1zing. The pellets were immersed in warm water for several minutes followed by agitation 1n a laboratsry blender. The sample was f~ltered using cheesecloth and resoaked in water followed by agltat~on. Th~s process was repeated four t~mes to remove the residual PVOH. The fine flbers were then dried. The photomicrographs taken w1th a SEM (scannlng el ectron ~ croscope) 1nd~cated fiber diameters ~n the range of 1 to 10~.
~xample 9 A mixture of 50X Vlnex 2025 PVOH, 40~ Profax 6823 polypropylene, and lOX SurlynTM 8660 ethylene/methacryl~c acid copolymer ionomer available from duPont was extruded ln a 1" K~ on extruder at 180-200C at an RPM of 8 and a rate of 800 grams/hour. The extruded strand was hot drawn and chopped into pellets. The pellets were immersed in water, agitated, and then filtered. The a~itation and flltration process was repeated several t~mes to remove res1dual PVOH.
Exampl~ lQ
A mlx~ure o~ 50X Vinex 2034 PVOH, ~ thermoplast1c PVOH available from Air Products and Che~cals, Inc. and ~OX NJCT (New Jersey Curbslde Taillngs: as described in Plast~cs Engineerlng, p. 33, Feb. 1990) was extruded in a 1" Killlon extruder at 180C-200~C. The NJCT was ground ~n liquid N2 to 50 mesh size prior to extrusian. The extruded sample was hot drawn and pellet~zed. Ths pellets were l~mersed ~n water and agitated ln a laboratory blender. The product was flltered and the agitation/filtrat~on process was repeated several tlme$ to re~ove the residual PVOH.
Examplç 11 A m~xture of 50X Vlnex 2025 PWH, 30X polypropylene (Profax ~823~, and 20X ethylene-methacrylic ac1d lonomer ~Surlyn 8660) was extruded 1n a 1"
K~llion extruder at 180-200C, RPM ~ 9, rate . 732 grams/hour. The extruded 20 strand was hot drawn, cooled and pelletlzed. The pellets were immersed 1n water and ag~tated ln a laboratory blender. The product was then filtered.
The agitation/filtration procedure was repeated several times to remove residual PVOH.

Example 12 The procedure of example 9 was repeated except an additional 10 mlnutes agitatlon t~me was conducted before the ~nal f~ltratlon.

Exam~Q 13 A mlxture of 50X Vinex 2025 PVOH and 50X Profax 6523 polypropylene was extruded 1n a 1" K~llion extruder at 180-200C, RPM ~ 9.1, rate ~ 672 grams/hours. The extruded strand was hot drawn, coo1ed and pelletized. The pallets were 1mmersed ~n water and ag~tat~d ln a laboratory blender. The product was then ~iltered. The ag~tat~on/~iltration procedure was repeated several t1mes to remove resldual PVOH.

2 ~

Example 14 A mixture of 40~ thermoplastic poly~vinyl alcohol) and 60 polypropylene (Profax 65233 was extruded ~n a 1" K~ll;on extruder, RPM ~
10.3, rate ~ 56~ grams/hour. The extruded strand was hot drawn, cooled and pelletized. The pellets were immersed ~n water and agitated in a laboratory blender. The product was fi1tered and the ag~tation/f~ltraton procedure was repeated several times to remove residual PVOH.

The procedure o~ example 9 was repeated except that the ayitation tlme prlor to flnal f~ltrat10n was an additional 40 minutes.

Ex~mple 1~
The procedure of example 10 was repeated except the granulated NJCT
ut11~zed was ~mmersed ~n water and the floating particles were removed and dried. This removed the PET and PVC particles. The granulated produ~t was used as ~s without liquid N2 grinding.

Exampl~ 17 A mixture of 60X Vinex 2025 PVOH and 40~ Profax 65~3 polypropylene was extruded in a 1" Killion extruder at 180-200~C, RPM ~ 8.8, rate Y 684 grams/hour. The extruded strand was hot drawn, cooled and pelletlzed. The pellets were inunersed ln water, agitated.in a ~Jarlng blender and filtered.
The ag~tat~on/f~ltrat~on process was repeated several times ~o remove res i dual PVOH .

ExamDl ~ 1 ~
A mlxture of 70~ V~nex 2025 PWH and 30X Profax 6523 polypropylen~ was extruded in a 1" K~ on Dxtruder at lBO-200C, RPM ~ 9.5, rate 8 648 grams/hour. The extruded strand ~as hot drawn, cooled and pelletized. The pellets were immersed in wat0r, ag~tated in a Waring ~lender and filtered.
The ag~tat~on flltration process was repeated several tlmes to remove residual PVOH.

2 ~

Example 19 A rheological test protocol was established to determine the effectiveness of various ultraf1ne fibers as rheology modifiers for adhes~ves, caulks, etc. A commercial DGEBA-type epoxy resln (Dow Chemical's DER 331) was chosen as the base material for all of the evaluations. The complex viscosity of the various fiber-epoxy res~n mixtures (as a function oF shear rate) was used to d~fferent~ate among materials. In add~tion to APCI-developed f~bers, two commerc~al materials were examined as rheology modifiers (DuPont's PE PULP TA-12 and Hercules' PULPEX EDH). Many of the fibers of this ~nvention exhibited superior viscosity lmprovement (at fiber equivalent loadings) compared to the co~mercial samples. The procedures described below were used to prepare the f~ber-epoxy mixtures and obtain the rheologica1 data.

T~st Proced~res Each fiber was washed with d~st~lled water to remove any residual poly(~inyl alcohol) and dried at room temperature under vacuum overnight.
The f~bers were then mixed with Dow Chem~cal's DER 331 epoxy resin at fiber we~ght load1ngs of 1.0 and 2.5X. A~ter v~gorous mixlng (by hand) with a metal spatula at room temperature, the fiber-el30xy resln mixture was degassed by placing it ln an oven at 50-70C and hold~ng it under vacuum overn~ght. Upon removal fro~ the oven, some o~ the mixtures displayed nonuniformity, i.e. the fibers separated from the epoxy. Each of the mixtures were gently re-mixed to assure samp1e uni~ormity and allowed to cool to room temperature. The mixtures were stored under vacuum until they wQre ready to be tested.
The complex viscosity-shear rate data ~ere obtained at 27C on a Rheometr~cs RMS-605 Mechan~cal Spectrometer us1ng a cone and plate fixture (cone angle: 0.106 radian; plate ~ 25.4 mm d1ameter; gap: 0.050 mm). A
shear rate range oF 0.0628 - 99.54 rad/sec was employed. Dynamic (as opposed to steady) testing (using a strain of lOOO was util1zed for all samples. The dynamic mode of testlRg reduced the possibility of fiber orientation during the test measurement. A sample of neat DER 331 was also evaluated ~or comparison purposes. Rheological data were collected at five ~6~2~

frequencies for each decade of frequency. All of the measurements were made in a nitrogen atmosphere.
A small amoun~ of each ultra~ine fiber-epoxy mixture was placed on the plate and the cone was lowered until a gap o~ 0~08-0.11 mm was reached. The bulk of the excess mixture was removed w1th a metal spatula. The sample was allowed to reach 27C after which the gap was set to 0.050 mm. Any additional excess of the m~xture was removed so that a stra19ht edge formed between the outside edge of the plate, the sample, and the outsîde edge of the cone. The samples were allowed to thermally re equ~llbrate to 27C
10 prior to testing. Care was taken during sample loading to ensure that no normal force ex~sted between the cone and the plate (due to the presence of ~1bers on the order of 0.05 mm located under the central part of the cone).

Using the test procedure described above, the following f7ber samples were evalua~ed as rheology modifiers: DuPont's PE PULP TA-12, Hercules' PULPEX EDH and Example 13 fibers. Flber load~ngs of 1.0 and 2.5 weight percent in DER 331 epoxy res1n were examined.
Table 2 summarizes the (averaged) complex v~scos~ty-shear rate data for each of these f~ber-modlfied epoxy samples (at the 1.0 wt% load~ng) and the control DFR 331 sample. The data reported ln Table 2 are the average of two or three runs for each compositlon. For each dupl~cate run the samples were reloaded into the rheometer to el~m~nate the possibl1~ty of sample or~entatlon (as a result of the flrst dynamic rate sweep).
The data ln Table 2 indlcate the marked ~ncrease ~n v~scoslty with the addlt~on of ultraf1ne flbers. Except for the DER 331 samp1e, which exh~bited Newton1an behav~or (shear rate independent v~scoslty), each of the samples d~splayed shear thinning, i.e. decreasing v1scos~ty with ~ncreasing shear rate. The viscosity of the f~ber-modlfled epoxies began to approach the v~scosity of the neat DER 331 at the hlgher shear rates.
The fluctuat~ons ln viscosity for DER 331 (at the low shear rates) are evidence that the co~plex viscosity data at the lower shear rates are subject to greater error. Th~s is due to the fact that the observed torques at these low shear rates were at the lower l~m~t o~ the transducer.
3~

2 ~ 2 1:

Most notable in Table 2 is the fact that Example 13 f~bers provided higher v~scosities over the ~ntire shear rate range than either of the commerc~al samples. These data imply that lower fiber loadings of Example 13 can be used to obtain equivalent perfor~ance to the duPont and Hercules 5 materials.

Summary of Complex Vlscos7ty-Shear Rate Data (at 27C) for DER 331, PE PULP TA-12, PULPEX EDH, and Example 13 fibers ~hear Ratç _ ~omplex Yiscos7ty _ DER 331pF PULP TA-12~ PULPEX EDH~Example 13 fibers ~Rad.JSec]~Poise] ~Poise~ ~Poise] ~Poise~

0 ~ 06280 220 1 41 0 980 2300 o.ogg53 100 1030 730 1610 0.1578 110 g2~ 5~0 1220 0.2500 130 685 480 960 0.3963 110 56~ 425 745 0.628U 125 495 380 61 0.99~4 120 ~30 340 505 1.578 125 380 3~ 435 2.500 120 340 280 385 3.9~3 120 310 260 350 6.2B1 120 280 245 315 9.954 120 260 230 290 15.78 120 24~ ~15 270 2~.00 120 220 200 250 39.63 120 210 190 235 6Z.81 120 195 185 ZZ0 99.54 120 185 175 205 * 1.0 we7ght % fiber load7ng The (averaged) complex vissosity-shear rate data (at 27C) for these f7ber-modtf7ed epoxies (at the 2.5 weight X loading~ and the control DER 331 sample are presented in Table 3. The trends ~n the data are equ~valent to those observed at the 1.0 weight X fiber loadings.
The data in Table 3 summarizes the complex viscosity-shear rate data at the 2.5 wtX ~iber loading.

2 ~

,9 Summary of Complex Viscoslty-Shear Rate Data (at 27C) for DER 331, PE PULP TA-12, PULPEX EDH, and example 13 fibers _ _ Shear Rate Complex V~scosity DER 331PE PULP TA-12~PULPEX EDH*Example 13 fibers ~Rad.~Sec~CPolse] ~Poise] ~Po~se] ~Poise~

~.062~ 220 5780 3~10 11000 1~ 0.09953 1~0 4~30 2880 751û
0 . 1 57~ 3200 2320 5300 O . 25û0 1 30 24~0 1 79~ 3820 0.3963 110 1~70 1420 2780 0 . 6280 1 ~5 1 460 1 1 50 2030 0 . 9954 1 20 1 1 70 925 1 51 0 1 . ~78 1 ~5 935 755 1 1 20 2 . 500 120 760 625 B80 3 . 96~ 1 20 640 530 71 5 6.~81 1~0 555 46~ 600 9.954 120 490 415 515 1 5 . 78 1 20 435 375 450 25 . 00 1 2~ 39~) 34~) ~05 39 . 63 1 20 350 305 365 62 . 81 1 20 31 5 280 330 99.54 120 290 260 300 2.5 weight X fiber load~ng Example 21 Table ~ summarizes the (averayed~ complex v~scoslty-shear rate data for each of the noted f1ber samples. The data reported in Table 4 are the average of two or three runs for each composition. For each duplicate run the samples were reloaded into the rheometer to ellminate the possibility of sample orientation as a result of the first dynamlc rate sweep.

2 ~

_ 20 -Complex Viscosity in Poise (27C) Rate (RAD/SEC) Sample Description 0.0628 0.2500 2.500 25.00 _ _ . . . .

lX Example 8 1380 620 315 215 2.5X Example 8 6250 2320 665 3~5 lX Example 9 1950 785 350 225 2.5X Example 9 9100 3420 935 44~
lX Example 10 1560 720 355 230 2.5X Example 10 6800 2710 840 420 1~ Example 11 1720 710 320 210 2.5~ Example 11 6760 ~530 725 355 lX Example 12 1950 790 355 225 2.5i! Example 12 11,100 4060 960 425 lX Example 14 960 435 250 190 2.5X Example 14 6080 1900 580 335 1~ Example 15 1900 9ûO 380 240 2.5X Example 15 10,0003710 935 430 7X Example 16 805 530 280 210 2.5X Example 16 3250 1750 590 360 lX Example 17 1890 775 340 230 2.5~ Example 17 11,4004510 1010 450 lX Example 18 2070 825 355 230 2.5X Example 18 11,8004680 1080 460 Example 22 The fibers of example 8 were ~mmersed in water and mixed in a pulp disintegrator. The resultant slurry was formed into mats using the Br~t~sh Standard handsheet former following TAPPI Method 205. The synthetic pulp mats were then removed and dried.

2 ~ 2 ~1 Example 23 The mats o~ example 8 after drying were subjected to oil sorptlon tests.
The oil sorption test consisted of a preweighed fiber mat being ~mmersed in a pan of Sunoco Ultra lOW30 motor oil and allowing the mat to soak for various time intervals. The sheet was then transferred to a dry pan and weighed. For the ultra-fine fiber sample of example 8 sheets of various weights were prepared as per the procedure of example 22. The oil sorption results are given i n Tabl e 5 .

Table ~
~eight of Fiber Mat Oil Sorption (X) ~grams) 10 min. 20 min. 30 min.40 mln.

1 . 8909 1, 906~ 1, 968~
1 53 . 72~6 346X1 9 945X 1, 956%
6 . 7659 1 9 245X 1, 406% 1 9 504%1 9 507%
Examplg 24 A sample of NJCT (New Jersey Curbs1de Tail~n~s) was obtained (Plastics Engineering, p. 33, Feb. 1990~. The sample was washed, extruded and cryoground. A blend of 45X Vinex 2034 PVOH, 4!iX cryoground NJCT and lOX
Surlyn 9020 ethylene-methacrylic acid ~onomer available from duPont was extruded at 180-190C hot drawn, cooled and pelletized. The pellets were water extracted as per the procedure noted in example 8. The dried fine fibers of this example were formed into mats using the procedure of example 26. The oil sorption results on these mats as per the sorption procedure noted in Example 23 are listed in Table 6.

Table 6 30 Weight of Fiber Mat 011 Sorption (X) ~grams) 10 mln. 20 min. 30 min.
~ . _ , . _ 1.9397 895% 895X --4.2119 585X 638~ 713~
5.8040 486X ~95X 534X

2~4~

A sample of NJCT (as described ~n example 24) was washed in water and the granules whlch floated were separated and drled. This sample was blended with 5 Vinex 2025 PVOH 50/50 by ~t.~ extruded ln a 1" single screw Killion extruder (L/D ~ 30/1), hot drawn, cooled over dry 1ce, and pellet1zed. The pellets were extracted o~ the poly(vinyl alcohol) as per the procedure o~ example 8 and ultra-f~ne fibers resulted. The fibers were formed into mats as per the procedure in example 22. Nominally, 2, 4 and 6 gr. mats were prepared for oil 10 sorpt~on stud~es as per example 23. The oil sorption results are given in Table 7.

Ex~mple 2fi A blend o~ 50% V~nex 2025 PWH/40X Profax 6823 polypropylene/10~ Surlyn 15 8660 ethylene-methacrylic acld ~onomer was extruded using a 1" Kill~on extruder equlpped with mixing sections (L/D ~ 30/1) at 180-190C. The extruded strand was hot drawn (10ll draw ratio) cooled and pelletized. The extruder RPM was 8.0 and the product rate was 800 grams/hr. The resultant product was extracted with water to re~ove the po1y(vinyl alcohol~ and liberate the fibers as per the procedure ln example 8. The fibers were formed into mats as per the procedure in example 22. Nominally, 2, 4, and 6 gr. mats were prepared for oil sorption studies as per example 23. The oil sorpt~on results are givQn in Table. 7.

Exam~le 27 ~Con~rQl Example~
A fine fiber sample of Pulpex EDH was obta~ned ~rom Hercules for evaluation. Pulpex EDH is a polyethylene f~ne ~ib~r produced specifically for sprayed ce~l~ng texture compounds. The properties are: density Y 0.96 g/cc;
melting point ~ 132C, ~iber length 0.6-1.2 mm, fiber diameter ~ 30-40~.
Pulpex EDH was agitated into a pulp-like conslstency and mats w~re prepared as per the procedure noted in example 22 and tested for oil sorption as per the procedure ~n example 23. The oil sorption results on nom~nal 2 gr, 4 gr and 6 gr sheets are listed in Table 7.

3s 2 ~

Comparison of Oil Sorption Results Oil Sorption (weight % increase) 5 Sample Designation (>20 minutes imm~rsion) 2 gr.4 gr. 6 gr.

Control Example (27) 9g8X811% 743X
Example 25 1,293~ 1,014% 900%
Example 26 1,076X 751% 675 Example 28 A blend of 50~. Vinex 2025 PVOH and 50X tby weight) of Profax 6723 polypropylene obtained from Himont was extruded in a 1" Killion extruder (3011 L/D~ at 200C. The extruded strand w~s or~ented, cooled and chopped into 1/8"-3/16" pellets. The extruder RPM was 8.5, the extrusion rate was 730 grams/hour, the extruded strand take-up rate was ~65 ft.tmin. The pellets were soaked in water and agitated in a labsratory blender for 30 seconds to one minute. The sample was filtered to remove the water soluble components.
The water soluble fract10n (Vinex 2025 P W H) was devolatilized in an air circulating oven at 80-90C for several days. A~ter drying, 70X of the V~nex 2025 PVOH was reeovered. The extracted pellets were reextracted with w~ter and ag~tated several t~mes (using a laboratory blender) and then dried. The resultant dried product was a fluffy fibrous mass of fine polypropylene ~ibers.
The second stage of this experiment involved the testing and recycle of the extracted Vinex 2025 P W H. The melt flow of the original Vinex 2025 PVOH
is compared with the extruded, extracted and dried Vinex 2025 PVOH below:

Melt Fl~w (2G0C. 44 Psi~
30 Sa~ple Dgscription _ dg/m~n. da/min.
V~nex 2025 PVOH 5.0 5.2 Extruded and Extracted 5.1 4.7 Recovered Vinex 20~5 PVOH

2~6~2~

The recovered Vinex 2D25 PVO~ had virtually ~dentical melt flow (thus melt viscosity) as the control Vi nex 2025 PWH.
The recovered Vinex 2025 PVOH and eontrol Vlnex 2025 PWH Sû/50 blend was extruded with Profax 6723 polypropylene ~n a 1" K~1110n extruder.
(Composition by wt. ~ 25X recovered Vinex 2025 P W H/25X control Vinex 2025 PWH/50% Profax 6723 polypropylene). The extruded strand was oriented, cooled and chopped into 1l8"-3/16" pellets. The extruder RPM was 15.3, the rate was 918 grams/hour and the take-up rate was ~0 ft/mln. The pellets were extracted of poly(vinyl alcohol) by agitat~on in a laboratory blender followQd by lo filtration. This procedure was repeated several t~es.
Another compar~son was made by extrud~ng a blend of 5DX of the recovered Vinex 20~5 PVOH and 50~ Profax 6723 polypropylene in a 1" Killion extruder 30/1 L/D at 200C. The extruded strand was oriented, cooled and chopped into 1/8"-3/16" pellets. The extruder RPM was 21.3, the product rate was 870 grams/hour and the take-up rate was 50 ft/min. The pellets were extracted of poly(vlnyl alcohol) by agitation in a laboratory blender ~ollowed by filtrat~on. This procedure was repeated several times to remove substant~al1y all of the PVOH.
The three samples of fîne polypropylene fibers were tested for f~brous thixotropy using DER-331 epoxy resin as the liquid phase. Comparisons ~ith the control DER-331, and 1 and 2.5 wt. X addit10n to DER-331 as well as a melt blown fiber utilized for fibrous thixotropy appl~catlons (Pulpex EDH). The data are listed ~n Table 8.

2 ~

Viscosity (Poise) 50/50 50/50 lX 2.5X Control Control Recycle/ Recycle~ 100~ lOOX
Shear.Pulpex Pulpex Sample Sample Control Control Recycle Recycle Rate~B=~ EDH EDH 1~ 2.5X _ 1%_2 ~__ 1.0% 2.5%
3.0628220 980 361~1140 6130 129~5930 59~ 4660 ~.0995100 730 28~0 795 4350 9554170 440 2590 0.158110 560 2320 650 3200 77030~0 370 1620 a 0.25130 4B~ 1790 530 2430 6202320 300 1140 0.40110 425 1~0 440 184Q 5051780 255 870 0.~3125 38() 1150 375 1410 4301370 235 695 0.995. 1~0 340 925 325 1080 3651060 210 560 1.57~120 300 755 305 830 320 ~25 200 455 2.5 120 280 625 260 ~50 275 655 180 375 3.96120 260 530 235 545 255 550 170 325 2Q 6.28120 245 465 220 460 230 470 165 290 9.9512~ 230 415 205 400 210 ~10 155 265 i5.~120 215 375 190 355 195 370 15~ 245 120 200 34~ 180 320 185 335 145 225 3~.6120 190 305 170 290 175 305 140 210 62. a12G 185 230 160 265 165 275 135 200 9~.5120 175 260 155 240 155 250 125 185 2 0 ~

Exam~le 29 A blend of 70% (by wt.) polystyrenQ (280,000 Mw:Aldrich) and 30~ Vinex 2025 PVOH was extruded in a 1" Killion extruder at 200C, oriented by hot drawing, chopped and agitated in water. After PVOH extraction, a ultra-fine fibrous product was recoYered and dried.

Exam~1e 3~
A blend of 50X (by wt.) V~nex 2025 PWH and 50X styrene/acrylonitrile copolymer (30X AN content:Scientlfic Polymer Products; Cat. ~495) was prepared in a 1" Killion extruder at ~00 210C9 oriented by hot drawing, chopped and ag;tated in water. APter extractlon o~ PVOH, 0.2 to 0.3m fibers were observed based on scanning electron microscopy studies~

Example 3L
A blend of 50X by wt. Vinex 2025 PWH and 50X by wt. of a polystyrene foam product (CushionpakTM polystyrene: produced by CPI Packaging Co., Marlboro, NJ) was extruded ~n a 1" Killion extruder at 180-200C. Prior to extrusion, the foam was heated to 150C, allowed to shrink, ground-up and mixed with Vinex 2025 PVOH pellets. The extrusion RPM was 14 and the product 20 rate was 900 grams/hour. The extrudate was oriented, pelletized, and agitated in water to extract the poly(vinyl alcohol). After several extractions, the resultant dried product was ultra-fine fibers of polystyrene.Example 32 Example ~2 A blend of 75% of the styrene/acrylon~trile copolymer of example 30 and 25~ (by wt.~ of Vlnex 2025 PWH was extruded in a 1" Killion extruder, oriented by hot drawing, pelletized, agitated ~n water followed by extraction of poly(v~ny1 alcohol). The resultant product was a fiber mass of styrene/acrylon~trile ultra-fine fibers.
Hav~ng thus described the present invention, what is now deemed appropriate for Letters Patent ~s set out in the following appended claims.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the production of ultra-fine polymeric fibers said process comprising:
mixing granular thermoplastic polymeric material with thermoplastic poly(vinyl alcohol), extruding the resultant mixture through a die, followed by subjecting the mixture to an orientation step, chopping the extruded oriented material into desired lengths, and thereafter extracting the thermoplastic poly(vinyl alcohol) to produce ultra-fine polymeric fibers.

2. The process of Claim 1 wherein said thermoplastic polymeric material is a polyolefin.

3. The process of Claim 2 wherein said thermoplastic polymeric material is polypropylene.

4. The process of Claim 3 wherein said thermoplastic polymeric material is polystyrene.

5. The process of Claim 1 wherein said thermoplastic polymeric material is post-consumer polymeric scrap.

6. The process of Claim 5 wherein said post-consumer polymeric scrap comprises polymeric material selected from the group consisting of polyolefins, polystyrene, poly(ethylene terephthalate), poly(vinyl chloride), poly(vinylidene chloride), ethylene/vinyl alcohol copolymers, cellulosic products, high acrylonitrile copolymers and mixtures thereof.

7. The process of Claim 1 wherein said granular thermoplastic polymeric material is formed by grinding polymeric material in liquid nitrogen.

8. The process of Claim 1 wherein a defoaming agent is added to the polymeric material/poly(vinyl alcohol) mixtures.

9. The process of Claim 8 wherein said defoaming agent is an ethylene oxide/propylene oxide based block copolymer.

10. The process of Claim 1 wherein the poly(vinyl alcohol) is extracted from the polymeric fibers by agitation in a water slurry.

11. The process of Claim 1 wherein the extracted poly(vinyl alcohol) is recycled and reused in this process.

12. The process of Claim 1 wherein the thermoplastic poly(vinyl alcohol) is formed by adding a plasticizer to poly(vinyl alcohol).

13. The process of Claim 12 wherein said plasticizer is glycerine.

14. The process of Claim 1 wherein said thermoplastic poly(vinyl alcohol) is from 72-99% hydrolyzed.

15. The process of Claim 1 wherein said thermoplastic poly(vinyl alcohol) is from 78-94% hydrolyzed.